This invention relates to motor cooling systems, and more particularly, to an electric motor that utilizes two different cooling air sources depending upon a state of the host vehicle.
Vehicles, such as aircraft, typically include rotating machinery to move fluids throughout various vehicle systems to operate the vehicle. The rotating machinery, such as a fan or a compressor, is typically driven by an electric motor. During operation, the electric motor requires cooling to maintain desirable operating temperatures of the motor. Typically, forced air from movement of the vehicle (i.e. ram air) is used to cool the motor. Alternatively, dedicated cooling equipment, such as a blower fan driven by an additional motor, is used to provide motor cooling.
Ram air cooling is effective when the vehicle is in motion, however, when the aircraft is on the ground or moving at a relatively slow speed, the ram air may not provide the desired amount of cooling. Dedicated cooling equipment may offer improved cooling air flow at low vehicle speeds, however, dedicated cooling equipment may undesirably reduce system reliability, increase weight, and add expense.
Accordingly, there is a need for a compact and inexpensive motor cooling system that maintains a motor at a desired operating temperature during various travel states of the vehicle.